1. Field of Invention
An exemplary embodiment of the present invention relates to an electric thermostat of a cooling system in a vehicle, More particularly, the present invention relates to a glow plug that allows the heating temperature of an electric thermostat to rapidly reach a desired temperature.
2. Description of Related Art
In general, thermostats for vehicles can be disposed between an engine and a radiator, and function to maintain a coolant at an appropriate temperature by automatically opening/closing in accordance with a change in temperature of the coolant and controlling the flow rate of the coolant flowing to the engine.
In the related art, most of thermostats for vehicle are mechanical thermostat structured such that the expansion force of was, which expands in accordance with the temperature of a coolant, is transmitted to a piston and a valve is opened/closed by the force.
However, such mechanical thermostats operates in the way of operating in accordance with opening/closing temperatures set as regulation temperatures of a coolant, that is, in the way of simply opening/closing the valve only at predetermined temperatures. Accordingly, considering the recent tendency that the performance and efficiency of vehicles are gradually increased, there is a limit in actively dealing with changes in driving circumstances and other conditions.
Currently, variable control types of electric thermostats that maintain the temperature of the engine coolant in an optimal status while making up for the drawbacks of the mechanical thermostats have been developed,
The electric thermostats can keep an engine optimally cooled, by controlling the temperature of the engine coolant in accordance with the driving circumstances such as the status of load applied to the vehicle, and can be expected to improve fuel efficiency and reduce exhaust gas in comparison to the mechanical thermostats.
An example of the electric thermostats has a structure in which wax and a film resistance type of film are included, heat is generated by a heater supplied with power, the wax is expanded by the heat of the heater, and a piston is pushed by the expansion force, such that a value is operated.
The electric thermostats using the film resistance type of heater or other heaters in the related art take 50˜70 seconds to reach a desired temperature of 300-350° C.
Therefore, there is a problem in the related art in that as it takes a lot of time to increase the heating temperature of the heater to a desired temperature, it is difficult to control the temperature of the coolant in real time and it is also difficult to improve fuel efficiency of a vehicle.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.